1. Field of the Invention
The present general inventive concept relates to a multilayer printed circuit board, and more particularly to a multilayer printed circuit board capable of reducing an electromagnetic wave radiated within a sectional region of the multilayer printed circuit board.
2. Description of the Related Art
In general, a multilayer printed circuit board refers to a printed circuit board including a plurality of layers. As disclosed in Korean Unexamined Patent Publication No. 2006-93519 (electromagnetic wave shielding structure in multilayer printed circuit board), a conventional multilayer printed circuit board includes a top surface of a first layer and a bottom surface of a fourth layer on which various components constituting an electronic circuit and a plurality of patterns for connecting the components to each other are formed, a power source surface of a third layer which is divided into a 1.5V surface, a 3.3 V surface and a 5V surface so as to provide DC power for operating the components, and a ground surface of a second layer having a reference voltage. In addition, although it is not disclosed in detail in Korean Unexamined Patent Publication No. 2006-93519, the conventional multilayer printed circuit board includes a strip line which is provided between the power source surface and the ground surface so as to connect the components to each other.
In such a conventional multilayer printed circuit board, as current flows through the strip line, signals are transferred between the components. However, when current flows through the strip line, an electromagnetic wave is generated according to Maxwell's equations. In addition, the electromagnetic wave is transmitted to a sectional surface of the multilayer printed circuit board by means of the power source surface and the ground surface serving as transmission paths for the wave.
However, in such a conventional multilayer printed circuit board, the electromagnetic wave generated from the strip line is propagated so that the electromagnetic wave is radiated around a sectional region of the multilayer printed circuit board. If the multilayer printed circuit board is used for a broadcasting receiver, a broadcasting receive antenna is installed around the sectional region of the multilayer printed circuit board. In this case, a receive sensitivity of the broadcasting receive antenna is degraded due to interference from the electromagnetic wave that radiates around the sectional region of the multilayer printed circuit board.
That is, in the broadcasting receiver, the broadcasting receive antenna is generally placed around the sectional region of the multilayer printed circuit board due to the structure of the product, and in this case, the electromagnetic wave radiated around the sectional region of the multilayer printed circuit board causes interference, thereby lowering a signal-to-noise ratio of the broadcasting receive antenna.